diff --git a/lib/include/srslte/common/common.h b/lib/include/srslte/common/common.h
index 7156fbfc9..c6ad06402 100644
--- a/lib/include/srslte/common/common.h
+++ b/lib/include/srslte/common/common.h
@@ -44,6 +44,14 @@
 #define SRSLTE_N_DRB           8
 #define SRSLTE_N_RADIO_BEARERS 11
 
+#define HARQ_DELAY_MS 4
+#define MSG3_DELAY_MS 6
+#define HARQ_TX(tti) ((tti+HARQ_DELAY_MS)%10240)
+#define HARQ_RX(tti) ((tti+(2*HARQ_DELAY_MS))%10240)
+
+#define TTIMOD_SZ   10
+#define TTIMOD(tti)  (tti%TTIMOD_SZ)
+
 // Cat 3 UE - Max number of DL-SCH transport block bits received within a TTI
 // 3GPP 36.306 Table 4.1.1
 #define SRSLTE_MAX_BUFFER_SIZE_BITS  102048
diff --git a/srsenb/hdr/mac/scheduler_ue.h b/srsenb/hdr/mac/scheduler_ue.h
index 3653ff65c..c163ed570 100644
--- a/srsenb/hdr/mac/scheduler_ue.h
+++ b/srsenb/hdr/mac/scheduler_ue.h
@@ -172,7 +172,7 @@ private:
   // Allowed DCI locations per CFI and per subframe    
   sched_dci_cce_t dci_locations[3][10];   
 
-  const static int SCHED_MAX_HARQ_PROC = 8; 
+  const static int SCHED_MAX_HARQ_PROC = 2*HARQ_DELAY_MS;
   dl_harq_proc dl_harq[SCHED_MAX_HARQ_PROC]; 
   ul_harq_proc ul_harq[SCHED_MAX_HARQ_PROC]; 
   
diff --git a/srsenb/hdr/mac/ue.h b/srsenb/hdr/mac/ue.h
index b879d040b..0f95a1144 100644
--- a/srsenb/hdr/mac/ue.h
+++ b/srsenb/hdr/mac/ue.h
@@ -120,7 +120,7 @@ private:
   
   uint32_t nof_failures; 
   
-  const static int NOF_HARQ_PROCESSES = 8; 
+  const static int NOF_HARQ_PROCESSES = 2*HARQ_DELAY_MS;
   srslte_softbuffer_tx_t softbuffer_tx[NOF_HARQ_PROCESSES];
   srslte_softbuffer_rx_t softbuffer_rx[NOF_HARQ_PROCESSES];
 
diff --git a/srsenb/hdr/phy/phch_common.h b/srsenb/hdr/phy/phch_common.h
index 00a59d969..6c7c064cf 100644
--- a/srsenb/hdr/phy/phch_common.h
+++ b/srsenb/hdr/phy/phch_common.h
@@ -78,13 +78,13 @@ public:
   mac_interface_phy *mac; 
   
   // Common objects for schedulign grants 
-  mac_interface_phy::ul_sched_t ul_grants[10];
-  mac_interface_phy::dl_sched_t dl_grants[10];
+  mac_interface_phy::ul_sched_t ul_grants[TTIMOD_SZ];
+  mac_interface_phy::dl_sched_t dl_grants[TTIMOD_SZ];
   
   // Map of pending ACKs for each user 
   typedef struct {
-    bool is_pending[10]; 
-    uint16_t n_pdcch[10];
+    bool is_pending[TTIMOD_SZ];
+    uint16_t n_pdcch[TTIMOD_SZ];
   } pending_ack_t;
   std::map<uint16_t,pending_ack_t> pending_ack;
   
diff --git a/srsenb/hdr/phy/phch_worker.h b/srsenb/hdr/phy/phch_worker.h
index 906e8b9d0..a84045920 100644
--- a/srsenb/hdr/phy/phch_worker.h
+++ b/srsenb/hdr/phy/phch_worker.h
@@ -73,12 +73,12 @@ private:
   
   void work_imp();
   
-  int encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants, uint32_t sf_idx);
-  int decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch, uint32_t tti_rx);
-  int encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks, uint32_t sf_idx);
-  int encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants, uint32_t sf_idx);
-  int encode_pdcch_ul(srslte_enb_ul_pusch_t *grants, uint32_t nof_grants, uint32_t sf_idx); 
-  int decode_pucch(uint32_t tti_rx);
+  int encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants);
+  int decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch);
+  int encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks);
+  int encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants);
+  int encode_pdcch_ul(srslte_enb_ul_pusch_t *grants, uint32_t nof_grants);
+  int decode_pucch();
   
   
   /* Common objects */  
@@ -89,8 +89,9 @@ private:
 
   cf_t          *signal_buffer_rx; 
   cf_t          *signal_buffer_tx; 
-  uint32_t       tti_rx, tti_tx, tti_sched_ul, sf_rx, sf_tx, sf_sched_ul, tx_mutex_cnt;
-
+  uint32_t       tti_rx, tti_tx, tti_sched_ul;
+  uint32_t       sf_rx, sf_tx, tx_mutex_cnt;
+  uint32_t       t_rx, t_tx, t_sched_ul;
   srslte_enb_dl_t enb_dl;
   srslte_enb_ul_t enb_ul;
   
diff --git a/srsenb/src/mac/mac.cc b/srsenb/src/mac/mac.cc
index 6c8458540..03e192034 100644
--- a/srsenb/src/mac/mac.cc
+++ b/srsenb/src/mac/mac.cc
@@ -406,7 +406,7 @@ int mac::get_dl_sched(uint32_t tti, dl_sched_t *dl_sched_res)
   log_h->step(tti);
 
   if (!started) {
-    return 0; 
+    return 0;
   }
   
   if (!dl_sched_res) {
@@ -601,7 +601,7 @@ int mac::get_ul_sched(uint32_t tti, ul_sched_t *ul_sched_res)
   ul_sched_res->nof_phich = sched_result.nof_phich_elems;
   return SRSLTE_SUCCESS; 
 }
-
+  
 void mac::tti_clock()
 {
   timers_thread.tti_clock();
diff --git a/srsenb/src/mac/scheduler.cc b/srsenb/src/mac/scheduler.cc
index 539b7725f..73f121424 100644
--- a/srsenb/src/mac/scheduler.cc
+++ b/srsenb/src/mac/scheduler.cc
@@ -541,7 +541,7 @@ int sched::dl_sched_rar(dl_sched_rar_t rar[MAX_RAR_LIST])
                 pending_rar[j].rar_tti = 0;            
                 
                 // Save UL resources 
-                uint32_t pending_tti=(current_tti+6)%10;
+                uint32_t pending_tti=(current_tti+MSG3_DELAY_MS)%10;
                 pending_msg3[pending_tti].enabled = true; 
                 pending_msg3[pending_tti].rnti    = pending_rar[j].rnti; 
                 pending_msg3[pending_tti].L       = L_prb; 
@@ -677,7 +677,7 @@ int sched::ul_sched(uint32_t tti, srsenb::sched_interface::ul_sched_res_t* sched
   pthread_mutex_lock(&mutex);
 
   /* If dl_sched() not yet called this tti (this tti is +4ms advanced), reset CCE state */
-  if ((current_tti+4)%10240 != tti) {
+  if (HARQ_TX(current_tti) != tti) {
     bzero(used_cce, MAX_CCE*sizeof(bool));    
   }
   
@@ -685,9 +685,9 @@ int sched::ul_sched(uint32_t tti, srsenb::sched_interface::ul_sched_res_t* sched
   current_tti = tti; 
   sfn = tti/10;
   if (tti > 4) {
-    sf_idx = (tti-4)%10; 
+    sf_idx = (tti-HARQ_DELAY_MS)%10;
   } else {
-    sf_idx = (tti+10240-4)%10;
+    sf_idx = (tti+10240-HARQ_DELAY_MS)%10;
   }
   int nof_dci_elems   = 0; 
   int nof_phich_elems = 0; 
diff --git a/srsenb/src/mac/scheduler_harq.cc b/srsenb/src/mac/scheduler_harq.cc
index a6ae70d19..f5209b374 100644
--- a/srsenb/src/mac/scheduler_harq.cc
+++ b/srsenb/src/mac/scheduler_harq.cc
@@ -177,7 +177,7 @@ void dl_harq_proc::set_rbgmask(uint32_t new_mask)
 
 bool dl_harq_proc::has_pending_retx(uint32_t current_tti)
 {
-  return srslte_tti_interval(current_tti, tti) >= 8 && has_pending_retx_common(); 
+  return srslte_tti_interval(current_tti, tti) >= (2*HARQ_DELAY_MS) && has_pending_retx_common();
 }
 
 int dl_harq_proc::get_tbs()
diff --git a/srsenb/src/mac/scheduler_ue.cc b/srsenb/src/mac/scheduler_ue.cc
index 3eab6b33d..525494ad2 100644
--- a/srsenb/src/mac/scheduler_ue.cc
+++ b/srsenb/src/mac/scheduler_ue.cc
@@ -248,7 +248,7 @@ bool sched_ue::get_pucch_sched(uint32_t current_tti, uint32_t prb_idx[2])
   
   // First check if it has pending ACKs 
   for (int i=0;i<SCHED_MAX_HARQ_PROC;i++) {
-    if (((dl_harq[i].get_tti()+4)%10240) == current_tti) {
+    if (HARQ_TX(dl_harq[i].get_tti()) == current_tti) {
       uint32_t n_pucch = srslte_pucch_get_npucch(dl_harq[i].get_n_cce(), SRSLTE_PUCCH_FORMAT_1A, has_sr, &pucch_sched);
       if (prb_idx) {
         for (int i=0;i<2;i++) {
@@ -288,7 +288,7 @@ bool sched_ue::get_pucch_sched(uint32_t current_tti, uint32_t prb_idx[2])
 int sched_ue::set_ack_info(uint32_t tti, bool ack)
 {
   for (int i=0;i<SCHED_MAX_HARQ_PROC;i++) {
-    if (((dl_harq[i].get_tti()+4)%10240) == tti) {
+    if (HARQ_TX(dl_harq[i].get_tti()) == tti) {
       Debug("SCHED: Set ACK=%d for rnti=0x%x, pid=%d, tti=%d\n", ack, rnti, i, tti);
       dl_harq[i].set_ack(ack); 
       return dl_harq[i].get_tbs();
diff --git a/srsenb/src/phy/phch_common.cc b/srsenb/src/phy/phch_common.cc
index e4d91581e..719064324 100644
--- a/srsenb/src/phy/phch_common.cc
+++ b/srsenb/src/phy/phch_common.cc
@@ -48,8 +48,8 @@ void phch_common::set_nof_mutex(uint32_t nof_mutex_) {
 }
 
 void phch_common::reset() {
-  bzero(ul_grants, sizeof(mac_interface_phy::ul_sched_t)*10);
-  bzero(dl_grants, sizeof(mac_interface_phy::dl_sched_t)*10);
+  bzero(ul_grants, sizeof(mac_interface_phy::ul_sched_t)*TTIMOD_SZ);
+  bzero(dl_grants, sizeof(mac_interface_phy::dl_sched_t)*TTIMOD_SZ);
 }
 
 bool phch_common::init(srslte_cell_t *cell_, srslte::radio* radio_h_, mac_interface_phy *mac_)
diff --git a/srsenb/src/phy/phch_worker.cc b/srsenb/src/phy/phch_worker.cc
index 3a1fb8ca4..9cc87ddd9 100644
--- a/srsenb/src/phy/phch_worker.cc
+++ b/srsenb/src/phy/phch_worker.cc
@@ -176,11 +176,16 @@ cf_t* phch_worker::get_buffer_rx()
 void phch_worker::set_time(uint32_t tti_, uint32_t tx_mutex_cnt_, srslte_timestamp_t tx_time_)
 {
   tti_rx       = tti_; 
-  tti_tx       = (tti_ + 4)%10240; 
-  tti_sched_ul = (tti_ + 8)%10240; 
+  tti_tx       = HARQ_TX(tti_rx);
+  tti_sched_ul = HARQ_RX(tti_rx);
+  
   sf_rx        = tti_rx%10;
   sf_tx        = tti_tx%10;
-  sf_sched_ul  = tti_sched_ul%10;
+  
+  t_tx         = TTIMOD(tti_tx);
+  t_rx         = TTIMOD(tti_rx);
+  t_sched_ul   = TTIMOD(tti_sched_ul);
+  
   tx_mutex_cnt = tx_mutex_cnt_;
   memcpy(&tx_time, &tx_time_, sizeof(srslte_timestamp_t));
 }
@@ -245,7 +250,7 @@ void phch_worker::rem_rnti(uint16_t rnti)
     srslte_enb_ul_rem_rnti(&enb_ul, rnti);
     
     // remove any pending grant for each subframe 
-    for (uint32_t i=0;i<10;i++) {
+    for (uint32_t i=0;i<TTIMOD_SZ;i++) {
       for (uint32_t j=0;j<phy->ul_grants[i].nof_grants;j++) {
         if (phy->ul_grants[i].sched_grants[j].rnti == rnti) {
           phy->ul_grants[i].sched_grants[j].rnti = 0; 
@@ -265,8 +270,6 @@ void phch_worker::rem_rnti(uint16_t rnti)
 
 void phch_worker::work_imp()
 {
-  uint32_t sf_ack;
-
   if (!running) {
     return;
   }
@@ -290,48 +293,47 @@ void phch_worker::work_imp()
   srslte_enb_ul_fft(&enb_ul, signal_buffer_rx);
 
   // Decode pending UL grants for the tti they were scheduled
-  decode_pusch(ul_grants[sf_rx].sched_grants, ul_grants[sf_rx].nof_grants, sf_rx);
+  decode_pusch(ul_grants[t_rx].sched_grants, ul_grants[t_rx].nof_grants);
   
   // Decode remaining PUCCH ACKs not associated with PUSCH transmission and SR signals
-  decode_pucch(tti_rx);
+  decode_pucch();
       
   // Get DL scheduling for the TX TTI from MAC
-  if (mac->get_dl_sched(tti_tx, &dl_grants[sf_tx]) < 0) {
+  if (mac->get_dl_sched(tti_tx, &dl_grants[t_tx]) < 0) {
     Error("Getting DL scheduling from MAC\n");
     goto unlock;
   } 
   
-  if (dl_grants[sf_tx].cfi < 1 || dl_grants[sf_tx].cfi > 3) {
-    Error("Invalid CFI=%d\n", dl_grants[sf_tx].cfi);
+  if (dl_grants[t_tx].cfi < 1 || dl_grants[t_tx].cfi > 3) {
+    Error("Invalid CFI=%d\n", dl_grants[t_tx].cfi);
     goto unlock;
   }
   
   // Get UL scheduling for the TX TTI from MAC
-  if (mac->get_ul_sched(tti_sched_ul, &ul_grants[sf_sched_ul]) < 0) {
+  if (mac->get_ul_sched(tti_sched_ul, &ul_grants[t_sched_ul]) < 0) {
     Error("Getting UL scheduling from MAC\n");
     goto unlock;
   } 
   
   // Put base signals (references, PBCH, PCFICH and PSS/SSS) into the resource grid
   srslte_enb_dl_clear_sf(&enb_dl);
-  srslte_enb_dl_set_cfi(&enb_dl, dl_grants[sf_tx].cfi);
+  srslte_enb_dl_set_cfi(&enb_dl, dl_grants[t_tx].cfi);
   srslte_enb_dl_put_base(&enb_dl, tti_tx);
 
   // Put UL/DL grants to resource grid. PDSCH data will be encoded as well. 
-  encode_pdcch_dl(dl_grants[sf_tx].sched_grants, dl_grants[sf_tx].nof_grants, sf_tx);  
-  encode_pdcch_ul(ul_grants[sf_sched_ul].sched_grants, ul_grants[sf_sched_ul].nof_grants, sf_tx);
-  encode_pdsch(dl_grants[sf_tx].sched_grants, dl_grants[sf_tx].nof_grants, sf_tx);  
+  encode_pdcch_dl(dl_grants[t_tx].sched_grants, dl_grants[t_tx].nof_grants);
+  encode_pdcch_ul(ul_grants[t_sched_ul].sched_grants, ul_grants[t_sched_ul].nof_grants);
+  encode_pdsch(dl_grants[t_tx].sched_grants, dl_grants[t_tx].nof_grants);
   
   // Put pending PHICH HARQ ACK/NACK indications into subframe
-  encode_phich(ul_grants[sf_sched_ul].phich, ul_grants[sf_sched_ul].nof_phich, sf_tx);
+  encode_phich(ul_grants[t_sched_ul].phich, ul_grants[t_sched_ul].nof_phich);
   
-  // Prepare for receive ACK for DL grants in sf_tx+4
-  sf_ack = (sf_tx+4)%10; 
-  phy->ack_clear(sf_ack);
-  for (uint32_t i=0;i<dl_grants[sf_tx].nof_grants;i++) {
+  // Prepare for receive ACK for DL grants in t_tx+4
+  phy->ack_clear(TTIMOD(HARQ_TX(sf_tx)));
+  for (uint32_t i=0;i<dl_grants[t_tx].nof_grants;i++) {
     // SI-RNTI and RAR-RNTI do not have ACK
-    if (dl_grants[sf_tx].sched_grants[i].rnti >= SRSLTE_CRNTI_START && dl_grants[sf_tx].sched_grants[i].rnti <= SRSLTE_CRNTI_END) {
-      phy->ack_set_pending(sf_ack, dl_grants[sf_tx].sched_grants[i].rnti, dl_grants[sf_tx].sched_grants[i].location.ncce);      
+    if (dl_grants[t_tx].sched_grants[i].rnti >= SRSLTE_CRNTI_START && dl_grants[t_tx].sched_grants[i].rnti <= SRSLTE_CRNTI_END) {
+      phy->ack_set_pending(TTIMOD(HARQ_TX(sf_tx)), dl_grants[t_tx].sched_grants[i].rnti, dl_grants[t_tx].sched_grants[i].location.ncce);
     }
   }
   
@@ -364,7 +366,7 @@ unlock:
 }
 
 
-int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch, uint32_t tti)
+int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch)
 {
   srslte_uci_data_t uci_data; 
   bzero(&uci_data, sizeof(srslte_uci_data_t));
@@ -383,7 +385,7 @@ int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch,
     #endif
 
       // Get pending ACKs with an associated PUSCH transmission
-      if (phy->ack_is_pending(sf_rx, rnti)) {
+      if (phy->ack_is_pending(t_rx, rnti)) {
         uci_data.uci_ack_len = 1; 
       }
       // Configure PUSCH CQI channel 
@@ -406,7 +408,7 @@ int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch,
       
       srslte_ra_ul_grant_t phy_grant; 
       int res = -1;
-      if (!srslte_ra_ul_dci_to_grant(&grants[i].grant, enb_ul.cell.nof_prb, n_rb_ho, &phy_grant, tti%8)) {
+      if (!srslte_ra_ul_dci_to_grant(&grants[i].grant, enb_ul.cell.nof_prb, n_rb_ho, &phy_grant, tti_rx%8)) {
         if (phy_grant.mcs.mod == SRSLTE_MOD_64QAM) {
           phy_grant.mcs.mod = SRSLTE_MOD_16QAM;
         }
@@ -416,7 +418,7 @@ int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch,
                                                 grants[i].current_tx_nb, 
                                                 grants[i].data, 
                                                 &uci_data, 
-                                                tti);     
+                                                sf_rx);
       } else {
         Error("Computing PUSCH grant\n");
         return SRSLTE_ERROR; 
@@ -502,10 +504,9 @@ int phch_worker::decode_pusch(srslte_enb_ul_pusch_t *grants, uint32_t nof_pusch,
 }
 
 
-int phch_worker::decode_pucch(uint32_t tti_rx)
+int phch_worker::decode_pucch()
 {
-  uint32_t sf_rx = tti_rx%10;
-  srslte_uci_data_t uci_data; 
+  srslte_uci_data_t uci_data;
   
   for(std::map<uint16_t, ue>::iterator iter=ue_db.begin(); iter!=ue_db.end(); ++iter) {
     uint16_t rnti = (uint16_t) iter->first;
@@ -523,7 +524,7 @@ int phch_worker::decode_pucch(uint32_t tti_rx)
           uci_data.scheduling_request = true; 
         }
       }      
-      if (phy->ack_is_pending(sf_rx, rnti, &last_n_pdcch)) {
+      if (phy->ack_is_pending(t_rx, rnti, &last_n_pdcch)) {
         needs_pucch = true; 
         needs_ack = true; 
         uci_data.uci_ack_len = 1; 
@@ -539,7 +540,7 @@ int phch_worker::decode_pucch(uint32_t tti_rx)
       }
       
       if (needs_pucch) {
-        if (srslte_enb_ul_get_pucch(&enb_ul, rnti, last_n_pdcch, sf_rx, &uci_data)) {
+        if (srslte_enb_ul_get_pucch(&enb_ul, rnti, last_n_pdcch, t_rx, &uci_data)) {
           fprintf(stderr, "Error getting PUCCH\n");
           return SRSLTE_ERROR; 
         }
@@ -581,7 +582,7 @@ int phch_worker::decode_pucch(uint32_t tti_rx)
 }
 
 
-int phch_worker::encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks, uint32_t sf_idx)
+int phch_worker::encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks)
 {
   for (uint32_t i=0;i<nof_acks;i++) {
     uint16_t rnti = acks[i].rnti;
@@ -589,7 +590,7 @@ int phch_worker::encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks, ui
       srslte_enb_dl_put_phich(&enb_dl, acks[i].ack, 
                               ue_db[rnti].phich_info.n_prb_lowest, 
                               ue_db[rnti].phich_info.n_dmrs, 
-                              sf_idx);
+                              sf_tx);
       
       Info("PHICH: rnti=0x%x, hi=%d, I_lowest=%d, n_dmrs=%d, tti_tx=%d\n", 
           rnti, acks[i].ack, 
@@ -601,24 +602,24 @@ int phch_worker::encode_phich(srslte_enb_dl_phich_t *acks, uint32_t nof_acks, ui
 }
 
 
-int phch_worker::encode_pdcch_ul(srslte_enb_ul_pusch_t *grants, uint32_t nof_grants, uint32_t sf_idx)
+int phch_worker::encode_pdcch_ul(srslte_enb_ul_pusch_t *grants, uint32_t nof_grants)
 {
   for (uint32_t i=0;i<nof_grants;i++) {
     uint16_t rnti = grants[i].rnti;
     if (grants[i].needs_pdcch && rnti) {
-      if (srslte_enb_dl_put_pdcch_ul(&enb_dl, &grants[i].grant, grants[i].location, rnti, sf_idx)) {
+      if (srslte_enb_dl_put_pdcch_ul(&enb_dl, &grants[i].grant, grants[i].location, rnti, sf_tx)) {
         fprintf(stderr, "Error putting PUSCH %d\n",i);
         return SRSLTE_ERROR; 
       }
 
-      Info("PDCCH: UL DCI Format0  rnti=0x%x, cce_index=%d, L=%d, tti_tx=%d\n", 
-          rnti, grants[i].location.ncce, (1<<grants[i].location.L), tti_tx);
+      Info("PDCCH: UL DCI Format0  rnti=0x%x, cce_index=%d, L=%d, tpc=%d, tti_tx=%d\n",
+           rnti, grants[i].location.ncce, (1<<grants[i].location.L), grants[i].grant.tpc_pusch, tti_tx);
     }
   }
   return SRSLTE_SUCCESS; 
 }
 
-int phch_worker::encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants, uint32_t sf_idx)
+int phch_worker::encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants)
 {
   for (uint32_t i=0;i<nof_grants;i++) {
     uint16_t rnti = grants[i].rnti;
@@ -633,7 +634,7 @@ int phch_worker::encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_gra
           format = SRSLTE_DCI_FORMAT1A; 
         break;
       }
-      if (srslte_enb_dl_put_pdcch_dl(&enb_dl, &grants[i].grant, format, grants[i].location, rnti, sf_idx)) {
+      if (srslte_enb_dl_put_pdcch_dl(&enb_dl, &grants[i].grant, format, grants[i].location, rnti, sf_tx)) {
         fprintf(stderr, "Error putting PDCCH %d\n",i);
         return SRSLTE_ERROR; 
       }      
@@ -647,7 +648,7 @@ int phch_worker::encode_pdcch_dl(srslte_enb_dl_pdsch_t *grants, uint32_t nof_gra
   return 0; 
 }
 
-int phch_worker::encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants, uint32_t sf_idx)
+int phch_worker::encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants)
 {
   for (uint32_t i=0;i<nof_grants;i++) {
     uint16_t rnti = grants[i].rnti;
@@ -683,7 +684,7 @@ int phch_worker::encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants
           len = 1; 
         }        
         log_h->info_hex(ptr, len,
-                             "PDSCH: rnti=0x%x, l_crb=%2d, %s, harq=%d, tbs=%d, mcs=%d, rv=%d, tti_tx=%d\n", 
+                             "PDSCH: rnti=0x%x, l_crb=%2d, %s, harq=%d, tbs=%d, mcs=%d, rv=%d, tti_tx=%d\n",
                              rnti, phy_grant.nof_prb, grant_str, grants[i].grant.harq_process, 
                              phy_grant.mcs[0].tbs/8, phy_grant.mcs[0].idx, grants[i].grant.rv_idx, tti_tx);
       }
@@ -693,7 +694,7 @@ int phch_worker::encode_pdsch(srslte_enb_dl_pdsch_t *grants, uint32_t nof_grants
       int                     rv[SRSLTE_MAX_CODEWORDS] = {grants[i].grant.rv_idx, 0};
 
 
-      if (srslte_enb_dl_put_pdsch(&enb_dl, &phy_grant, sb, rnti, rv, sf_idx, d, SRSLTE_MIMO_TYPE_SINGLE_ANTENNA, 0))
+      if (srslte_enb_dl_put_pdsch(&enb_dl, &phy_grant, sb, rnti, rv, sf_tx, d, SRSLTE_MIMO_TYPE_SINGLE_ANTENNA, 0))
       {
         fprintf(stderr, "Error putting PDSCH %d\n",i);
         return SRSLTE_ERROR; 
diff --git a/srsue/hdr/mac/mac.h b/srsue/hdr/mac/mac.h
index a306af187..d19f668bf 100644
--- a/srsue/hdr/mac/mac.h
+++ b/srsue/hdr/mac/mac.h
@@ -109,7 +109,7 @@ private:
   
   static const int MAC_MAIN_THREAD_PRIO = 5; 
   static const int MAC_PDU_THREAD_PRIO  = 6;
-  static const int MAC_NOF_HARQ_PROC    = 8;
+  static const int MAC_NOF_HARQ_PROC    = 2*HARQ_DELAY_MS;
 
   // Interaction with PHY 
   srslte::tti_sync_cv   ttisync; 
diff --git a/srsue/hdr/phy/phch_common.h b/srsue/hdr/phy/phch_common.h
index aa64fe9ea..39e9e9685 100644
--- a/srsue/hdr/phy/phch_common.h
+++ b/srsue/hdr/phy/phch_common.h
@@ -138,7 +138,7 @@ namespace srsue {
       uint32_t I_lowest; 
       uint32_t n_dmrs;
     } pending_ack_t;
-    pending_ack_t pending_ack[10];
+    pending_ack_t pending_ack[TTIMOD_SZ];
     
     bool            is_first_tx;
 
diff --git a/srsue/src/mac/proc_bsr.cc b/srsue/src/mac/proc_bsr.cc
index 898943ab9..43694c1bc 100644
--- a/srsue/src/mac/proc_bsr.cc
+++ b/srsue/src/mac/proc_bsr.cc
@@ -368,7 +368,7 @@ bool bsr_proc::need_to_reset_sr() {
 
 bool bsr_proc::need_to_send_sr(uint32_t tti) {
   if (!sr_is_sent && triggered_bsr_type == REGULAR) {
-    if (srslte_tti_interval(tti,next_tx_tti)>0 && srslte_tti_interval(tti,next_tx_tti) < 10240-4) {
+    if (srslte_tti_interval(tti,next_tx_tti)>0 && srslte_tti_interval(tti,next_tx_tti) < 10240-HARQ_DELAY_MS) {
       reset_sr = false; 
       sr_is_sent = true; 
       Debug("BSR:   Need to send sr: sr_is_sent=true, reset_sr=false, tti=%d, next_tx_tti=%d\n", tti, next_tx_tti);
diff --git a/srsue/src/phy/phch_common.cc b/srsue/src/phy/phch_common.cc
index d49b1ced2..489d27197 100644
--- a/srsue/src/phy/phch_common.cc
+++ b/srsue/src/phy/phch_common.cc
@@ -195,13 +195,13 @@ void phch_common::set_dl_rnti(srslte_rnti_type_t type, uint16_t rnti_value, int
 }
 
 void phch_common::reset_pending_ack(uint32_t tti) {
-  pending_ack[tti%10].enabled = false; 
+  pending_ack[TTIMOD(tti)].enabled = false;
 }
 
 void phch_common::set_pending_ack(uint32_t tti, uint32_t I_lowest, uint32_t n_dmrs) {
-  pending_ack[tti%10].enabled  = true; 
-  pending_ack[tti%10].I_lowest = I_lowest;       
-  pending_ack[tti%10].n_dmrs = n_dmrs;            
+  pending_ack[TTIMOD(tti)].enabled  = true;
+  pending_ack[TTIMOD(tti)].I_lowest = I_lowest;
+  pending_ack[TTIMOD(tti)].n_dmrs = n_dmrs;
   Debug("Set pending ACK for tti=%d I_lowest=%d, n_dmrs=%d\n", tti, I_lowest, n_dmrs);
 }
 
@@ -211,12 +211,12 @@ bool phch_common::get_pending_ack(uint32_t tti) {
 
 bool phch_common::get_pending_ack(uint32_t tti, uint32_t *I_lowest, uint32_t *n_dmrs) {
   if (I_lowest) {
-    *I_lowest = pending_ack[tti%10].I_lowest;
+    *I_lowest = pending_ack[TTIMOD(tti)].I_lowest;
   }
   if (n_dmrs) {
-    *n_dmrs = pending_ack[tti%10].n_dmrs;
+    *n_dmrs = pending_ack[TTIMOD(tti)].n_dmrs;
   }
-  return pending_ack[tti%10].enabled;
+  return pending_ack[TTIMOD(tti)].enabled;
 }
 
 /* The transmisison of UL subframes must be in sequence. Each worker uses this function to indicate
diff --git a/srsue/src/phy/phch_recv.cc b/srsue/src/phy/phch_recv.cc
index dad2c82b8..647226384 100644
--- a/srsue/src/phy/phch_recv.cc
+++ b/srsue/src/phy/phch_recv.cc
@@ -715,11 +715,11 @@ void phch_recv::run_thread() {
 
               worker->set_sample_offset(srslte_ue_sync_get_sfo(&ue_sync)/1000);
 
-              /* Compute TX time: Any transmission happens in TTI4 thus advance 4 ms the reception time */
+              /* Compute TX time: Any transmission happens in TTI+4 thus advance 4 ms the reception time */
               srslte_timestamp_t rx_time, tx_time, tx_time_prach;
               srslte_ue_sync_get_last_timestamp(&ue_sync, &rx_time);
               srslte_timestamp_copy(&tx_time, &rx_time);
-              srslte_timestamp_add(&tx_time, 0, 4e-3 - time_adv_sec);
+              srslte_timestamp_add(&tx_time, 0, HARQ_DELAY_MS*1e-3 - time_adv_sec);
               worker->set_tx_time(tx_time, next_offset);
               next_offset = 0;
 
diff --git a/srsue/src/phy/phch_worker.cc b/srsue/src/phy/phch_worker.cc
index 1c9abc1ca..e6c0050e2 100644
--- a/srsue/src/phy/phch_worker.cc
+++ b/srsue/src/phy/phch_worker.cc
@@ -335,7 +335,7 @@ void phch_worker::work_imp()
                  &ul_action.softbuffers[0], ul_action.rv[0], ul_action.rnti, ul_mac_grant.is_from_rar);
     signal_ready = true; 
     if (ul_action.expect_ack) {
-      phy->set_pending_ack(tti + 8, ue_ul.pusch_cfg.grant.n_prb_tilde[0], ul_action.phy_grant.ul.ncs_dmrs);
+      phy->set_pending_ack(HARQ_RX(tti), ue_ul.pusch_cfg.grant.n_prb_tilde[0], ul_action.phy_grant.ul.ncs_dmrs);
     }
 
   } else if (dl_action.generate_ack || uci_data.scheduling_request || uci_data.uci_cqi_len > 0) {
@@ -663,7 +663,7 @@ bool phch_worker::decode_pdcch_ul(mac_interface_phy::mac_grant_t* grant)
   char timestr[64];
   timestr[0]='\0';
 
-  phy->reset_pending_ack(tti + 8); 
+  phy->reset_pending_ack(HARQ_RX(tti));
 
   srslte_dci_msg_t dci_msg; 
   srslte_ra_ul_dci_t dci_unpacked;
@@ -776,7 +776,7 @@ void phch_worker::set_uci_sr()
 {
   uci_data.scheduling_request = false; 
   if (phy->sr_enabled) {
-    uint32_t sr_tx_tti = (tti+4)%10240;
+    uint32_t sr_tx_tti = HARQ_TX(tti);
     // Get I_sr parameter   
     if (srslte_ue_ul_sr_send_tti(I_sr, sr_tx_tti)) {
       Info("PUCCH: SR transmission at TTI=%d, I_sr=%d\n", sr_tx_tti, I_sr);
@@ -793,7 +793,7 @@ void phch_worker::set_uci_periodic_cqi()
   int cqi_max       = phy->args->cqi_max;
   
   if (period_cqi.configured && rnti_is_set) {
-    if (period_cqi.ri_idx_present && srslte_ri_send(period_cqi.pmi_idx, period_cqi.ri_idx, (tti+4)%10240)) {
+    if (period_cqi.ri_idx_present && srslte_ri_send(period_cqi.pmi_idx, period_cqi.ri_idx, HARQ_TX(tti))) {
       if (uci_data.uci_ri_len) {
         uci_data.uci_cqi[0] = uci_data.uci_ri;
         uci_data.uci_cqi_len = uci_data.uci_ri_len;
@@ -802,7 +802,7 @@ void phch_worker::set_uci_periodic_cqi()
         uci_data.uci_pmi_len = 0;
         Info("PUCCH: Periodic RI=%d\n", uci_data.uci_cqi[0]);
       }
-    } else if (srslte_cqi_send(period_cqi.pmi_idx, (tti+4)%10240)) {
+    } else if (srslte_cqi_send(period_cqi.pmi_idx, HARQ_TX(tti))) {
       srslte_cqi_value_t cqi_report;
       if (period_cqi.format_is_subband) {
         // TODO: Implement subband periodic reports
@@ -868,8 +868,8 @@ void phch_worker::set_uci_aperiodic_cqi()
 
 bool phch_worker::srs_is_ready_to_send() {
   if (srs_cfg.configured) {
-    if (srslte_refsignal_srs_send_cs(srs_cfg.subframe_config, (tti+4)%10) == 1 && 
-        srslte_refsignal_srs_send_ue(srs_cfg.I_srs, (tti+4)%10240)        == 1)
+    if (srslte_refsignal_srs_send_cs(srs_cfg.subframe_config, HARQ_RX(tti)%10) == 1 &&
+        srslte_refsignal_srs_send_ue(srs_cfg.I_srs, HARQ_TX(tti))        == 1)
     {
       return true; 
     }
@@ -889,7 +889,7 @@ void phch_worker::encode_pusch(srslte_ra_ul_grant_t *grant, uint8_t *payload, ui
   char timestr[64];
   timestr[0]='\0';
   
-  if (srslte_ue_ul_cfg_grant(&ue_ul, grant, (tti+4)%10240, rv, current_tx_nb)) {
+  if (srslte_ue_ul_cfg_grant(&ue_ul, grant, HARQ_TX(tti), rv, current_tx_nb)) {
     Error("Configuring UL grant\n");
   }
   
@@ -919,7 +919,7 @@ void phch_worker::encode_pusch(srslte_ra_ul_grant_t *grant, uint8_t *payload, ui
 #endif
 
   Info("PUSCH: tti_tx=%d, n_prb=%d, rb_start=%d, tbs=%d, mod=%d, mcs=%d, rv_idx=%d, ack=%s, ri=%s, cfo=%.1f Hz%s\n",
-         (tti+4)%10240,
+         HARQ_TX(tti),
          grant->L_prb, grant->n_prb[0], 
          grant->mcs.tbs/8, grant->mcs.mod, grant->mcs.idx, rv,
          uci_data.uci_ack_len>0?(uci_data.uci_ack?"1":"0"):"no",
@@ -950,7 +950,7 @@ void phch_worker::encode_pucch()
     gettimeofday(&t[1], NULL);
 #endif
 
-    if (srslte_ue_ul_pucch_encode(&ue_ul, uci_data, last_dl_pdcch_ncce, (tti+4)%10240, signal_buffer[0])) {
+    if (srslte_ue_ul_pucch_encode(&ue_ul, uci_data, last_dl_pdcch_ncce, HARQ_TX(tti), signal_buffer[0])) {
       Error("Encoding PUCCH\n");
     }
 
@@ -966,7 +966,7 @@ void phch_worker::encode_pucch()
   float gain = set_power(tx_power);  
   
   Info("PUCCH: tti_tx=%d, n_cce=%3d, n_pucch=%d, n_prb=%d, ack=%s%s, ri=%s, pmi=%s%s, sr=%s, cfo=%.1f Hz%s\n",
-         (tti+4)%10240,
+         HARQ_TX(tti),
          last_dl_pdcch_ncce, ue_ul.pucch.last_n_pucch, ue_ul.pucch.last_n_prb, 
        uci_data.uci_ack_len>0?(uci_data.uci_ack?"1":"0"):"no",
        uci_data.uci_ack_len>1?(uci_data.uci_ack_2?"1":"0"):"",
@@ -987,7 +987,7 @@ void phch_worker::encode_srs()
   char timestr[64];
   timestr[0]='\0';
   
-  if (srslte_ue_ul_srs_encode(&ue_ul, (tti+4)%10240, signal_buffer[0])) 
+  if (srslte_ue_ul_srs_encode(&ue_ul, HARQ_TX(tti), signal_buffer[0]))
   {
     Error("Encoding SRS\n");
   }
@@ -1002,7 +1002,7 @@ void phch_worker::encode_srs()
   float gain = set_power(tx_power);
   uint32_t fi = srslte_vec_max_fi((float*) signal_buffer, SRSLTE_SF_LEN_PRB(cell.nof_prb));
   float *f = (float*) signal_buffer;
-  Info("SRS:   power=%.2f dBm, tti_tx=%d%s\n", tx_power, (tti+4)%10240, timestr);
+  Info("SRS:   power=%.2f dBm, tti_tx=%d%s\n", tx_power, HARQ_TX(tti), timestr);
   
 }